Should I blame my mother in law?

Two weeks ago I had to leave my kids with my mother in law for about a week while I was in the hospital recovering from surgery. When I went to pick them up they where both clearly sick, runny nose/cough,etc., and she has the nerve to tell me that my 3 year daughter was just faking the whole thing, that she had been almost all week! I called all that week to check in on them and NOTHING was mentioned of them being sick. The poor thing ended up with bronchitis and and ear infection and was sick for weeks. Then if that was not enough, I left them with her long enough to go to go back to the surgeons for a follow up exam and my daughter ends up "accidentally" running into the tip of her nasty cigarette and gets a small burn on her lip. I am so ticked, I have told her that I HATE smoking and to not do it around my children before. And she goes ahead and smokes while playing outside running with them? I think I may scream! I only left them with her before because I had no other option, I don't have any family myself and my husband works. I just thought I could trust my children with their own grandmother, but I guess not. At this point I don't really want her to EVER see my children again. I will never forgive her for all of this bs.